How Sandia Rad-Hardened the Intel 8085 for Nuclear Warheads and Deep Space

Starting in the late 1970s, Sandia National Laboratories built its own chip fab in Albuquerque to make parts the commercial market wouldn’t supply: radiation-hardened ICs for nuclear weapons and space missions. By 1982, working on 4-inch wafers at a 2-micron node, Sandia had recreated chips like RCA’s 1802 for the Galileo Jupiter probe — over 50,000 ICs for the mission and its backups alone. That same year the lab began converting Intel’s HMOS 8085 into a rad-hard CMOS part, the SA3000, ballooning the design from roughly 6,500 transistors to 18,000, with the instruction-decoder PLA proving the hardest piece to translate.

The engineering payoff was dramatic. Built on an n-on-n+ epitaxial substrate with extensive guard rings, hardened oxides, and aggressive latchup control, and run at up to 11V for radiation headroom, the SA3000 survived 1 million rads with just a 25% speed hit — about ten times its original design goal, and orders of magnitude beyond the ~1,000 rads fatal to humans. It still runs the altitude and fuzing computer in the W88 475kt warhead carried on the Trident II SLBM, and flew on Ball Aerospace star trackers and the CRRES radiation-study satellite.

The program also illustrates the politics of sovereign chip production. Around 1984–85 the government handed fab operations to Allied Signal, a contractor with no fab experience, slowing output and frustrating Sandia management. Harris later commercialized the design in 1990 as the HS1/HS9-80C85RH, derated to 5V and 2MHz versus the SA3000’s 10MHz, in space-grade and military-grade screening tiers.